This project consists of an ultrastructural and biochemical investigation of secretory processes in the ventral prostate of the male rat in vivo and in a tissue-slice system. Secretion is followed biochemically by assaying samples of medium collected at regular intervals for protein and marker enzymes of cytoplasmic organelles, e.g., acid phosphatase (lysosomes), cytochrome oxidase (mitochrondria). A number of agents, including dihydrotestosterone, and selected neurotransmitters and blockers, are being studied for their effects on secretion. The ultrastructural effects of these agents in prostatic epithelium are being investigated by electron microscopy and cytochemistry.